Max Lamp Lumen defines the maximum luminous intensity that an LED headlamp can support, beyond which the headlamp would be damaged in a very short time. For this reason, LED headlights are normally set to a lower operating brightness, because the further away from the threshold of the Max Lamp, the more the headlight operates in less extreme conditions and ensures better durability.
In LED underwater lights there is some confusion, as some manufacturers often advertise only the Max Lamp, but the user wants to know the exact operating brightness (in English "fixture") that can be expected and also know how far the manufacturer has kept from the maximum threshold.